Heat motor power unit for domestic waste compactor

ABSTRACT

A refuse compactor having an electrically controlled heat motor compacting means characterized by a refuse compacting ram movable in a main chamber which is subdivided by a resilient sleeve into concentric outer and inner annular cavities with the outer cavity containing thermally responsive material and the inner cavity containing hydraulic fluid. As the thermal material expands under the influence of a heating element therein the hydraulic fluid is compressed within the sleeve to force the ram in a waste compacting direction. A regulating valve controls the flow of the hydraulic fluid to and from an accumulator in conjunction with the energization of the heating element providing substantially instant return of the ram to its full cycle position.

United States Patent Brucken [4 Nov. 13, 1973 HEAT MOTOR POWER UNIT FORDOMESTIC WASTE COMPACTOR Inventor: Byron L. Brucken, Dayton, OhioAssignee: General Motors Corporation,

Detroit, Mich.

Filed: June 1, 1972 Appl. No.: 258,567

US. Cl 100/52, 60/23, 100/229 A, 100/266, 100/269 R Int. Cl B30b 15/22Field of Search 60/23; 100/229 A, 100/269 R, 52, 266

References Cited UNITED STATES PATENTS Boyd 100/269 X Noakes et al.

Swales et al. Carlson 60/23 Welsh 100/266 X Primary Examiner-Billy J.Wilhite Att0rneyWilliam S. Pettigrew et a1.

[ 57 ABSTRACT A refuse compactor having an electrically controlled heatmotor compacting means characterized by a refuse compacting rar'nmovable in a main chamberwhich is subdivided by a resilient sleeve intoconcentric outer and inner annular cavities .with the outer cavitycontaining thermally responsive material and the inner cavity containinghydraulic fluid. As the thermal material expands under the influence ofa heating element therein the hydraulic fluid is compressed within thesleeve to force the ram in a waste compacting direction. A regulatingvalve controls the flow of the hydraulic fluid to and from anaccumulator in conjunction with the energization of the heating elementproviding substantially instant return of the ram to its full cycleposition.

4 Claims, 4 Drawing Figures HEAT MOTOR POWER UNIT FOR DOMESTIC WASTECOMPACTOR This invention relates to waste compactors in general and moreparticularly to an electrically controlled heat motor compaction meansfor a domestic waste compactor.

The prior art is replete with compacting devices having ram platesdriven by various motive means such as electric motors, hydraulic fluidpumps, and air pressure compaction bags. For various reasons such ascost, maintenance and reliability none of the above systems have provedentirely satisfactory.

It is an object of this invention to solve the problem by providing arefuse compactor incorporating an integrated electrically controlledheat motor and hydraulic fluid drive system allowing substantiallyinstant return of the compacting ram after each compaction cycle.

A more specific object of this invention is provision of a domesticrefuse compactor in which a compaction electrically controlled heatmotor has a refuse compacting ram movable in a main chamber whichchamber is subdivided by a resilient sleeve into concentric outer andinner annular cavities in which the outer cavity contains thermallyresponsive material and the inner cavity contains hydraulic fluid suchthat as the thermally responsive material expands under the influence ofa heating element therein the hydraulic fluid is compressed to initiatea waste compacting cycle whereby after the refuse is compressedregulating valve means causes the hydraulic fluid to return to anaccumulator allowing substantially instant return of the ram to its fullcycle cooling position.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the drawings:

FIG. 1 is a perspective view of a domestic refuse compactor embodyingthe invention;

FIG. 2 is a rear elevational view of the refuse compactor with the rearpanel removed;

FIG. 3 is a broken longitudinal sectional view of the compaction heatmotor constructed in accordance with the present invention, the rambeing shown in its upwardly biased position at the start of a coolingcycle;

FIG. 4 is a fragmentary sectional view of the regulator valve taken online 4-4 of FIG. 3 together with a schematic wiring diagram of thecontrol system.

As shown in FIGS. 1 and 2, the trash compactor includes a verticallyelongated cabinet 12 having side walls 14, a rear wall (not shown) andan upper front wall 16 provided with a lower opening 18 inwhich a frontaccess door 20 is connected by hinges 22 to the inturned flange 23 ofthe left hand side panel 14. A re-, leasable door latch 24 and keeper 26are provided between the door 20 and the inturned flange of the righthand side wall 14 so that the door can be latched closed but can beselectively opened when the latch is released as shown in FIG. I. Anonoff push button electrical switch 30 is mounted on the front wall 16of the cabinet such that operation of the compactor may be manuallycontrolled by the switch.

The compactor casing 10 includes a top wall 32 and a base wall 33supporting an angle iron framework 34 comprising a pair of spacedhorizontally disposed top 36 and bottom 38 angle members on each sideand running the length of the cabinet interconnected by a pair offorward vertical angles, one of which being shown at 40 in FIG. I, and apair of rear vertical angles 42 (FIG. 2). The framework furthercomprises a pair of transverse upper and intermediate horizontal bracesindicated at 44 and 46, respectively in FIG. 2 showing the frameworkrigidly assembled by suitable means such as by bolt members shown.

Compaction motive means, indicated generally at 50 in FIGS. 1 and 2, isprovided for compressing refuse material. The compaction means is shownvertically oriented between the upper braces 44 and the intermediatebraces 46 of the casing 10 and includes a lower elongated main cylinder52 provided with a ram member 54 extending axially of the main cylinderso as to pass through opening 51 in a sealed manner by O-ring seal 55and is shown at its full cycle position with ram member 54 raised to itsfullest extent.

The ram member 54 carries on its lower extremity a ram plate or platen56 suitably affixed thereto such that the ram plate can be verticallyraised or lowered to compress refuse located in a container which, inthe disclosed embodiment, is an opemtop rectangular metal containerslidably positioned on the bottom wall between the angles 38. In theform disclosed the container 58 prior to its use is lined with adisposable bag 60 having a top cuff 62 turned over the top edge of thecontainer and of a sufficient length so that the bottom of the bag restsupon the bottom of thecontainerfThe container 58 is of a rectangularconfiguration which allows the rectangular ram plate 56 when descendedon the ram to be introduced into the container to compress the refuseplaced therein.

As seen in FIGS. I and 2 the compaction motive means 50 is in the formof an integrated heat responsive thermal motor and hydraulic fluidtransmitting actua tor having means for biasing the output ram 54 in itsupper full cycle position which in the preferred form comprise aplurality of elongated resilient spring members. In the disclosedembodiment the ram plate 56 and ram 54 are resiliently urged in anupward direction by four coil tension springs 64 secured in quadrature,one of the springs being suitably connected adjacent each corner of theram plate 56 by a loop at one of its ends engaged around an eyelet 65welded to the upper surface of the ram plate. In the preferred formsuitable clips are struck from each end of horizontal top angles 44 suchthat the springs 64 are stretched in tension when the piston is drivendownward. It will be appreciated that the coil springs 64 also serve torestrict rotary movement of the ram plate during its travel.

The main cylinder 52 is closed by threadedly receiving upper covermember 66 and lower cover member 68, sealed by O-ring 69, to define acompression chamber in which is disposed a hollow boot 70 formed of aresiliently flexible elastomeric material such as soft rubber or thelike. The boot 70 comprises a concentric cylindrical sleeve 72 having adiameter substantially less than the inside diameter of the cylinderestablishing an outer cylindrical cavity 73 and an inner cylindricalcavity 74. The wall of the sleeve 72 merges at its upper end with aradially extending flange 75 having an integral annular O-ring seal 76on its outer periphery for reception within annular groove 78 of theupper cover member 66 such that when the threads are taken up a fluidtight seal is provided therebetwccn.

The lower end of the sleeve 72 is positioned between an upwardlyextending hub member 80, located on the inner face of the bottom cover68, and vertically extending return spacer flange portion 82 ofaperforated tube 84 positioned in concentric relation with ram 54. Thetube 84 extends the full height of the cylinder 52 with its upper endreceived in a downwardly extending cylindrical boss 86 on the undersideof the upper cover member 66.

The outer cylindrical cavity 73 provides a first pressure chamber thatis filled with a heat fusible material, such as paraffin wax, having adesignation N-paraffin wax C which fuses and expands at a predeterminedtemperature to produce hydraulic pressure changes within the outsidecavity 73. The inner cavity 74 provides a second pressure chanber thatcontains hydraulic fluid such as oil and upon the expansion of the heatfusible material a resultant compression force is exerted on theresilient sleeve 72 thereby causing the hydraulic fluid to transmit thepressure created in the outer cavity to the ram 54.

As the pressure increases in the outer cavity 73 the fusible waxmaterial exerts compressive forces at all points on the sleeve 72 suchthat the forces circumferentially and radially compress the sleeve 72uniformly toward the output ram 54. The hydraulic fluid pressure incavity 74 causes the ram member 54 to be forced downwardly out of themain cylinder and apply a considerably pressure through the ram plate 56to compact refuse in the container. ln the disclosed form of theinvention the working hydraulic pressure developed in cavity 74 is about9000 pounds per square inch such that with a ram diameter of the orderof 0.60 inch there is produced a resultant ram force of about 3,000pounds.

Accumulator means are provided in the form of a secondary cylinder 90having a cup-shaped cylindrical cap member 92 telescopically mounted onperipheral shoulder 88 of cover member 66 and sealed thereto by O-ring93. The upper cover 66 has a stem 95 extending axially of the cylinder52 and passing through concentric opening 94 into dished portion 96 ofthe cap 92 whereby the cap is retained in sealed relation on the cover66 by a smap ring 97.

As seen in FIG. 3, slidably positioned around the vertical stem 95 is acup-shaped spring loaded accumulator piston 100 whose outercircumferential wall 102 is slidably movable in an axial directionwithin ghe cap member 92 in a sealed manner by means of outer O- ringseal 103 and inner O-ring seal 104. The cupshaped piston 100 has acentral hub portion 105 which extends vertically to engage the dishedportion 96.0f the cap 92 to limit its upward travel. The piston 100,shown at its full cycle position, is axially movable on the stem 95 andis biased in a downward direction to force the hydraulic fluid thereininto the main cylinder 52 by compression coil spring 106 whose upper endengages the closed end of the cap member 92 and whose lower endsurrounds piston central annular trunnion 107 resting thereon. The blindend of the piston 100 and the upper cover member 66 define a fluidreservoir chamber 109 of the spring loaded accumulator. Suitable pistonposition switch means are provided which in the disclosed form includean L-shaped arm 108 extending upwardly from the upper edge of wall 102through aligned slot means in the cap 92 operative to depress and closea micro switch 127 to sense the fully extended downward travel of pistonfor a reason to be explained.

A heating element inthe form of heating coil 110 having a mean diameterof about 2.0 inches is concentrically located in the main cylinder 52 soas to be embedded in the wax material while the opposite ends of theheating coil are connected to the exterior electrical terminals 1 12 and1 14, which terminals are in turn connected to an appropriate source ofelectrical current and compactor control means to be described.

Referring to the schematic diagram shown in FIG. 4, terminals L and Lare adapted to be connected to a suitable source ofelectric power, suchas 110 volt alternating current. In one line 120, the on-off cut-outrelay switch 30 has a push-button contact member 121 which when depresedenergizes a solenoid 123 in electrical series with L via .line and L viaclosed switch 132 to hold contact member 121 closed. Member 121 ismechanically linked to contact bridging member 124 which closes acircuit by line 125 through the closed contact 126 of depressed microswitch 127 because of the extended spring biased position of the piston100. Line 128 is connected to the solenoid 129 of a relay 130 for ashuttle control two-way valve 136. The solenoid 129 is suitably linkedby shuttle rod 131 to a pair of double-pole, single throw switches 132and 133 of the relay 130. The normally closed switch 132 has one contactconnected by line 135 to contact 121 of push button switch 30 and switch132 has its other contact connected by line 134 to L The normally openswitch 133 is electrically connected by one contact to heating element110, which is in series with a temperature limiting thermostat 139 whilethe other contact of switch 133 is connected to solenoid 129.

As seen in FIG. 4 valve 136 includes a transversely extending valve bore140 that slidably receives a valve shuttle 142 therein. The bore 140 isclosed at its enlarged end by plug member 143 while the opposite end ofthe bore 140 remains open to receive relay rod 131 therein suitablyaffixed to one end of the shuttle. The shuttle 142 is provided withundercut land portions 144 and 146 separated by O-ring seal and theannular groove portion 148 which is dimensioned to seat resilientlybiased detent 150 urged into the groove 148 by compression spring 151 toretain the shuttle 142 in a closed position to prevent movement ofhydraulic fluid through passages 137 and 138. Annular land portions 152and 153 of the shuttle 142 have an annular groove therebetween forseating O-ring seal 154 and are normally disposed in enlarged bore 155.The undercut lands 144 and 146 are dimensioned so as to be slidablydisposed in the bore 140. In the disclosed form the bore 140 has adiameter of about 0.250 inches, the undercut portions 144 and 146 have acommon diameter of about 0.248 inches and the large bore 155 has adiameter of about 0.270 inches to slidably receive the lands 152 and 153whose diameter is about 0.268 inches.

When the valve shuttle 142 is in its closed position, shown in solidlines in FIG. 4, fluid under pressure is free to pass from the innercavity 74 of the heat motor through passage 138 into bore 140 and thenceinto bore 155 where it is blocked by elastomeric O-ring seal 154 insealed engagement with bore 155. During this pressure build-up thereciprocal ram 54 is axially driven downwardly in its refuse compactingstroke against the ram biasing means of springs 64. The fluid pressuredifferential between the larger lands 152, 153

and reduced diameter undercut portions 144, 146 causes the shuttle 142to be urged in the direction of the arrow under a working orlow-pressure condition in cavity 74. The resulting force acting on theshuttle 142 is not sufficient to overcome the biasing force of thespring 151 so that the shuttle 142 maintains its closed solid-lineposition of FIG. 4.

Upon the increase of the fluid pressure above a predetermined or triggerpressure in inner cavity 74, which inth instan form i9flh qslqt 9 999 Pthe sulting axial force on the shuttle 142 vi/ ill oJi'EcTiit'hE springbias 151 and detent 150 causing the shuttle 142 to move to its dashedline open position 142 thereby unseating and repositioning O-ring 154 inlarge bore 162. The fluid in cavity 74 under pressure from collapsingsleeve 70 is free to pass through passage means 138 and 137 into theaccumulator chamber 109 allowing the biasing springs 64 to instantlyinitiate return or travel of the ram. 7

The sequence of operation of the waste compactor is as follows: With theram 54 in its raised or full-cycle position the wax cooling periodstarts. As the wax material cools and-contracts the hydraulic fluid inchamber 109, under the spring bias pressure of the piston 100, is forcedto flow back through passage 137, the open valve 136 and passage 138into the main cylinder cavity 74. Accumulator position micro switch 127senses the downward or extended position of the piston 100, wherein thefluid or oil has re-filled the cavity 74 of the main cylinder by beingset by arm 108 to its closed position. After a quantity of trash isdeposited in the container 58 the operator depresses push button 121energizing the solenoid 129 and causing the shuttle 144 to be moved toits closed position energizing heater means 110 via the switch 133 toinitiate a new compaction cycle.

It will be appreciated that by virtue of applicants novel arrangement anintegrated electrically controlled heat motor and hydraulically actuatedoutput ram provide a downward force on ram plate or platen 56 sufficientto compact domestic refuse material in container 58 while attaining arapid upward return of theram, obviating the need for a delayed coolingperiod during which the wax material contracts and solidifies. Thedisclosed form of the invention utilizes approximately 26 cubic inchesof fusible wax material which undergoes an expansion of the order of 17percent by volume upon being heated. Thus, the instant ram returnresults from the unique combination of an accumulator regulatedhydraulic fluid and thermally expansible heat motor systems which coactto transmit the pressure from the thermally responsive wax material tothe output ram via an incompressible liquid thereby allowing for rapidupward return of the ram by means of the regulating valve andaccumulator circuitry.

In addition it should be noted that the rapid upward return is alsoassisted by having the temperature responsive wax material in cavity 73out of contact with the ram so that the wax material will not-impart alarge frictional drag on the ram 54. The hydraulic fluid serves as alubricant to minimize the sliding frictional drag of the ram 54.

lt should be noted that while the preferred embodiment of the heat motordiscloses housing means in the form of columnar main or primary cylinder50 and secondary accumulator cylinder 90 the invention contemplatesalternative forrns of housing means. For example, the accumulatorcylinder 90 could be mounted alongside of the primary cylinder 90 withsuitable passage means'effecti'ng hydraulic fluid communicationtherebetween without departing from the scope of the invention.

While the embodimentof the present invention constitutes a'preferredform, it is to be understood that other forms might be adopted.

I claim: 1

1. A force transmitting thermal heat motor for a compactor comprising,housing means containing main and secondary fluid-pressure cylinders, anelastic sleeve disposed concentrically in said main cylinder forminginner and outer annular fluid-tight cavities, said main cylinder havingan opening in one end in communication with said inner cavity, a rampositioned for slidable fluid-tight movement in said opening in areciprocal manner, means for biasing said ram into said main cylinder,platen means on the free end of said ram, hydraulic fluid within saidinner cavity and a thermally sensitive expansible mass of materialwithin said outer cavity, passage means connecting said main and secondary cylinders and effecting hydraulic fluid communicationtherebetween, a piston in said secondary cylinder, yieldable means forbiasing said piston in a direction tending to force hydraulic fluid fromsaid secondary cylinder into said primary cylindervvia said passagemeans, control means including valve means in said passage means forsupplying hydraulic fluid under pressure selectively between saidsecondary cylinder and said inner cavity, heating means disposed in saidouter cavity and having terminals for receiving an electrical currentfrom a source outside said housing means, whereby the energization ofsaid heating means causes the expansion of the mass of material andresultant pressure on said sleeve adapted to compress said sleeve andtransmit the pressure to the hydraulic fluid in said inner cavity tomove said ram outwardly from said main cylinder such that said platenmeans thereon applies a compaction force to the material, means biasingsaid valve means so as to normally close said passage means, said valvebiasing means being responsive to a predetermined amount of hydraulicfluid pressure within said inner cavity opening said passage meansthereby permitting the hydraulic fluid toreturn to said secondarycylinder, and said control means operative in response to the opening ofsaid valve means to deenergize said heater means such that said ram isreadily returned into said main cylinder by said ram biasing means.

2. In a refuse compactor having a support, means for holding refuse tobe compacted in -a preselected compacting position, a platen member,heat motor drive means carried on said support for driving said platenmember into said refuse-holding means to compact refuse receivedtherein, said heat motor drive means including main and secondaryfluid-pressure cylinders, an elastic sleeve disposed concentrically insaid main cylinder forming inner and outer annular fluid-tight cavities,said main cylinder having an opening in one end in communication withsaid inner cavity, a ram positioned for slidable fluid-tight movement insaid main cylinder opening in a reciprocal manner, said platen supportedon said ram, resilient means for biasing said ram into said maincylinder, hydraulic fluid within said inner'cavity, thermally sensitiveexpansible material within said outer cavity, passage means connectingsaid main and secondary cylinders and effecting hydraulic fluidcommunication therebetween, a piston in said secondary cylinder,yieldable means for biasing said piston in an extended direction tendingto force hydraulic fluid from said secondary cylinder into said maincylinder via said passage means, control means including a valve bodyhaving a cylindrical bore interrupting the flow of hydraulic fluidthrough said passage means, a valve shuttle element slidably disposedwithin said bore for movement selectively opening and closing of saidpassage means, means biasing said shuttle element in its closed positionsuch that when said valve shuttle element is moved to its open positioncommunication is established through said passage means, heating meansdisposed in said outer cavity and having terminals for receiving anelectrical current from a power source, whereby the energization of saidheating means causes the expansion of the material in said outer cavityand resultant pressure on said sleeve adapted to compress said sleeveand transmit the pressure to the hydraulic fluid in said inner cavity tomove said ram outwardly from said main cylincer, said valve'shuttlebeing responsive to the increase of the fluid pressure above apredetermined amount to overcome said shuttle biasing means and movesaid valve shuttle element to its open position and thereby permittingthe hydraulic fluid to flow into said secondary cylinder and therebyallow said ram biasing means to readily return said ram into said maincylinder, said control means including normally open heater switch meansresponsive to the movement of said valve shuttle element whereby saidheater switch means is closed to energize said heater means only whensaid valve shuttle element is in its closed position, said control meansincluding solenoid means operative for moving said valve shuttle elementto its closed position upon the return of said piston to its extendedposition.

3. In a refuse compactor comprising, a support frame, a cabinetenclosing said support frame having door means covering a lower accessopening in said cabinet, means for holding refuse to be compacted in apreselected compacting position within said lower opening, a platenmember, heat motor drive means carried on said support frame for drivingsaid platen downwardly into said refuse-holding means to compact refusereceived therein, apparatus for operating said ram comprising: main andsecondary fluid-pressure cylinders mounted on the support, an elasticsleeve disposed concentrically in said main cylinder forming inner andouter annular fluid-tight cavities, said main cylinder having an openingin one end in communication with said inner cavity, said ram positionedfor slidable fluidtight movement in said opening in a reciprocal manner,resilient means for biasing said ram into said main-cylinder, hydraulicfluid within said inner cavity, thermally sensitive expansible materialwithin said outer cavity, passage means connecting said main andsecondary cylinders and effecting hydraulic fluid communicationtherebetween, a piston in said secondary cylinder, yieldable means forbiasing said piston in an extended direction tending to force hydraulicfluid from said secondary cylinder into said main cylinder via saidpassage means, apparatus control means including a valve body having acylindrical bore interrupting the flow of hydraulic fluid through saidpassage means, a valve shut-,

tle element slidably disposed within said bore for movement selectivelyopening and closing of said passage means, means biasing said shuttleelement in its closed position such that when said shuttle is moved toits open position communication is established through said passagemeans, heating means disposed in said outer cavity and having terminalsfor receiving an electrical current from a power source, whereby theenergization of said heating means causes the expansion of the materialin said outer cavity and resultant pressure on said sleeve adapted tocompress said sleeve and transmit the pressure to the hydraulic fluid insaid inner cavity to move said ram outwardly from said main cylinder,said valve shuttle being responsive to the increase of the fluidpressure above a predetermined amount to overcome said shuttle biasingmeans and move said valve shuttle to its open position therebypermitting the hydraulic fluid to flow into said secondary cylinder,said control means including a relay having a solenoid operative whenenergized to move said valve shuttle element to its closed position,said solenoid connected in electrical series with a start switch,normally open piston position switch means connected in electricalseries with said start switch responsive upon said piston reaching itsextended position to close and thereby upon the closing of said startswitch to energize said solenoid to move said valve shuttle element toits closed position, and normally open heater switch means responsive tothe movement of said valve shuttle to its closed position to close saidheater switch means and energize said heater means to thereby initiate arefuse compaction cycle.

4. The refuse compactor of claim 3 wherein said secondary cylinder ismounted on the upper end of said main cylinder in axially alignedcolumnar fashion.

1. A force transmitting thermal heat motor for a compactor comprising,housing means containing main and secondary fluidpressure cylinders, anelastic sleeve disposed concentrically in said main cylinder forminginner and outer annular fluid-tight cavities, said main cylinder havingan opening in one end in communication with said inner cavity, a rampositioned for slidable fluid-tight movement in said opening in areciprocal manner, means for biasing said ram into said main cylinder,platen means on the free end of said ram, hydraulic fluid within saidinner cavity and a thermally sensitive expansible mass of materialwithin said outer cavity, passage means connecting said main andsecondary cylinders and effecting hydraulic fluid communicationtherebetween, a piston in said secondary cylinder, yieldable means forbiasing said piston in a direction tending to force hydraulic fluid fromsaid secondary Cylinder into said primary cylinder via said passagemeans, control means including valve means in said passage means forsupplying hydraulic fluid under pressure selectively between saidsecondary cylinder and said inner cavity, heating means disposed in saidouter cavity and having terminals for receiving an electrical currentfrom a source outside said housing means, whereby the energization ofsaid heating means causes the expansion of the mass of material andresultant pressure on said sleeve adapted to compress said sleeve andtransmit the pressure to the hydraulic fluid in said inner cavity tomove said ram outwardly from said main cylinder such that said platenmeans thereon applies a compaction force to the material, means biasingsaid valve means so as to normally close said passage means, said valvebiasing means being responsive to a predetermined amount of hydraulicfluid pressure within said inner cavity opening said passage meansthereby permitting the hydraulic fluid to return to said secondarycylinder, and said control means operative in response to the opening ofsaid valve means to deenergize said heater means such that said ram isreadily returned into said main cylinder by said ram biasing means. 2.In a refuse compactor having a support, means for holding refuse to becompacted in a preselected compacting position, a platen member, heatmotor drive means carried on said support for driving said platen memberinto said refuse-holding means to compact refuse received therein, saidheat motor drive means including main and secondary fluid-pressurecylinders, an elastic sleeve disposed concentrically in said maincylinder forming inner and outer annular fluid-tight cavities, said maincylinder having an opening in one end in communication with said innercavity, a ram positioned for slidable fluid-tight movement in said maincylinder opening in a reciprocal manner, said platen supported on saidram, resilient means for biasing said ram into said main cylinder,hydraulic fluid within said inner cavity, thermally sensitive expansiblematerial within said outer cavity, passage means connecting said mainand secondary cylinders and effecting hydraulic fluid communicationtherebetween, a piston in said secondary cylinder, yieldable means forbiasing said piston in an extended direction tending to force hydraulicfluid from said secondary cylinder into said main cylinder via saidpassage means, control means including a valve body having a cylindricalbore interrupting the flow of hydraulic fluid through said passagemeans, a valve shuttle element slidably disposed within said bore formovement selectively opening and closing of said passage means, meansbiasing said shuttle element in its closed position such that when saidvalve shuttle element is moved to its open position communication isestablished through said passage means, heating means disposed in saidouter cavity and having terminals for receiving an electrical currentfrom a power source, whereby the energization of said heating meanscauses the expansion of the material in said outer cavity and resultantpressure on said sleeve adapted to compress said sleeve and transmit thepressure to the hydraulic fluid in said inner cavity to move said ramoutwardly from said main cylincer, said valve shuttle being responsiveto the increase of the fluid pressure above a predetermined amount toovercome said shuttle biasing means and move said valve shuttle elementto its open position and thereby permitting the hydraulic fluid to flowinto said secondary cylinder and thereby allow said ram biasing means toreadily return said ram into said main cylinder, said control meansincluding normally open heater switch means responsive to the movementof said valve shuttle element whereby said heater switch means is closedto energize said heater means only when said valve shuttle element is inits closed position, said control means including solenoid meansoperative for moving said valve shuttle element to its clOsed positionupon the return of said piston to its extended position.
 3. In a refusecompactor comprising, a support frame, a cabinet enclosing said supportframe having door means covering a lower access opening in said cabinet,means for holding refuse to be compacted in a preselected compactingposition within said lower opening, a platen member, heat motor drivemeans carried on said support frame for driving said platen downwardlyinto said refuse-holding means to compact refuse received therein,apparatus for operating said ram comprising: main and secondaryfluid-pressure cylinders mounted on the support, an elastic sleevedisposed concentrically in said main cylinder forming inner and outerannular fluid-tight cavities, said main cylinder having an opening inone end in communication with said inner cavity, said ram positioned forslidable fluid-tight movement in said opening in a reciprocal manner,resilient means for biasing said ram into said main cylinder, hydraulicfluid within said inner cavity, thermally sensitive expansible materialwithin said outer cavity, passage means connecting said main andsecondary cylinders and effecting hydraulic fluid communicationtherebetween, a piston in said secondary cylinder, yieldable means forbiasing said piston in an extended direction tending to force hydraulicfluid from said secondary cylinder into said main cylinder via saidpassage means, apparatus control means including a valve body having acylindrical bore interrupting the flow of hydraulic fluid through saidpassage means, a valve shuttle element slidably disposed within saidbore for movement selectively opening and closing of said passage means,means biasing said shuttle element in its closed position such that whensaid shuttle is moved to its open position communication is establishedthrough said passage means, heating means disposed in said outer cavityand having terminals for receiving an electrical current from a powersource, whereby the energization of said heating means causes theexpansion of the material in said outer cavity and resultant pressure onsaid sleeve adapted to compress said sleeve and transmit the pressure tothe hydraulic fluid in said inner cavity to move said ram outwardly fromsaid main cylinder, said valve shuttle being responsive to the increaseof the fluid pressure above a predetermined amount to overcome saidshuttle biasing means and move said valve shuttle to its open positionthereby permitting the hydraulic fluid to flow into said secondarycylinder, said control means including a relay having a solenoidoperative when energized to move said valve shuttle element to itsclosed position, said solenoid connected in electrical series with astart switch, normally open piston position switch means connected inelectrical series with said start switch responsive upon said pistonreaching its extended position to close and thereby upon the closing ofsaid start switch to energize said solenoid to move said valve shuttleelement to its closed position, and normally open heater switch meansresponsive to the movement of said valve shuttle to its closed positionto close said heater switch means and energize said heater means tothereby initiate a refuse compaction cycle.
 4. The refuse compactor ofclaim 3 wherein said secondary cylinder is mounted on the upper end ofsaid main cylinder in axially aligned columnar fashion.